Milo g



(No Model.)

M. G. KELLOGG. MULTIPLE SWITGHBOARD.

No. 592,410. Patented Oct. 26,1897.

Nrrnn STATES PATENT muon.

MILO G. KELLOGG, OF CHICAGO, ILLINOIS, ASSIGNOR TO TI'IE KELLOGG SWITCI'IBOARD AND SUPPLY COMPANY, OE SAME PLACE.

NI ULT| PLE SWITCHBOARD.

SPECIFICATION forming part of Letters Patent No. 592,410, dated October 26, 1.897.

Application filed August 31, 1891. Serial No. 404,338. (No model.)

To all whom it may concern:

Be it known that I, MILO G. KELLOGG, of Chicago, in the county of Cook and State of Illinois, have invented certain new and useful Improvements in Multiple Switchboards for Telephone-Exchan ges, of which the following is a f ull, clear, concise, and exact description, reference being had to the accompanying drawings, forming a part of this specification.`

My invention relates more especially to a telephone-exchange system in which induc tioncoil translators are used at the central oiiice, one for each line. It is applicable to Y metallic-circuit or to ground-circuit systems or to a system in which the two kinds ot' lines are mixed.

My invention consists, iirst, in a system of line-annunciators and switching at the central otice which I shall describe and claim in detail.

It consists, secondly, in an organization for answering calls, making connections,and testing at the central ottice which I shall describe and claim in detail.

In the accompanying drawings, illustrating my invention, Figure l shows a front View of sections of two boards to which the same lines connect with the central-cnice apparatus and connections of two lines, one a metalliccircuit line and one a ground-circuit line. Fig. 2 shows an operators cord system to be used at each board. Fig. 3 shows an operators test system to be used at each board. Fig. 4 is a diagram of a subscribers-station apparatus to be used with each metallic-circuit line.

There are as many switchboards as required for the number of lines of the exchange. In Fig. l two boards are shown, (marked A A.) Each board has a metallic socket or contactpiece for each line adapted to receive and form connection with the switch-pl ugs shown in Fig. 2 and marked D D. These contactpieces are marked j j. y

I I are induction-coil translators, one for eachlineof the exchange. These translators have each an iron core and two coils or helices wound around the core, one of which is connected in the circuit of the line and may be called the mainline coil and the other of which is connected locally to the central office and may be called the local coil. Each translator has a relay-armature which is attracted by the core when a current of sufii cient strength is maintained in one ofthe coils, preferably the local coil. It has also a pair of contact-points normally open, but closed to each other when the armature is attracted and moved by the core.

w w are annunciators, of which there is one for each line. Each line is in circuit with the main-line coil of its translator.

The annunciator of each ground-circuit line is in the circuit of the line. The annunciator `of each metalliccircuit line is in a ground connection to the line. One of the contacts of a line-translator is connected to one side of the line-annunciator, and the other contact is connected to the other side of the annunciator. Vhen, therefore, the pair of contacts of the translator are closed to each other, the annunciator is shunted or short-circuited by the circuit which is established through the pair of contacts. One side of the local coil of each translator' is connected to all the contacts jj of the line to which the contacts belong. The other sides of the local coils are connected to the ground. L

In the operators cord system shown in Fig. 2 two pairs of switch-plugs are shown, each marked D D. Each pair of plugs has two calling-keys, (marked k 75,) a switch, (marked Y,) a clearing-out annunciator, (marked 1),) and a retardation-coil, (marked ai.) Each key has a lever normally in contact with a point and has another point against which the lever comes in contact when it is pressed away from the first-mentioned point.

t is the operators telephone. B is a battery, and B is a calling-generator. Each operator has a telephone. `One battery and one calling-generator will answer for the exchange.

The plugs are adapted to be inserted into the switch-holes of the terminals j j at their board and form connection with the terminals.

The switches Y Y have each a leverand two contact-bolts, on which the lever maybe alternately placed at the will of the operator.

One of the plugs of a pair is connected by a iicxible conductor to one of the keylevcrs IOO of the pair, and the other plug is similarly callin:, rgenerator. The lever of the switch connected to the other key-lever. The two points against which the levers normally press are connected together through the clearingout annunciator of the pair. The other contacts of the keys are grounded through the Yof the pair of plugs is connected to the circuitconnection which connects the contactpoints normally in contact with the key-levers, the connection being preferably between the two coils of the line-annunciator. One of the contact-bolts of the switch Y is connected through the retardation-coil of the pair of plugs to one side of the battery B'. The other contact-bolt is connected throughl the operators telephone to the same side of the battery. The other side of the battery is grounded.

The retardation-coils oo are electromagnetic self-induction coils with closed or practically or nearly closed magnetic circuits, and they offer very high impedance or self-induction effect to rapidly-alternating telephonecurrents, while affording a path of comparaduce a high degree of self-induction to rapl idly-chan gin g currents.

In the operators test system shown in Fig. x

3, T is the test-plug, and t the test receiving instrument. The plug is connected to a iieXible conductor and is adapted to be brought for testing into connection with any contactpiece j at its board' and is grounded through the test receiving instrument. Other pairs of plugs with their special apparatus may be added, as required, to the operators system and connected to the same substantially as required and as will be apparent to those skilled in the art. Each operator has one cord system and one test system, each suitably mounted and arranged for her work.

In the subscribers-station apparatus for metallic-circuit lines shown in Fig. et, 1 is the telephone-switchg 2, the callinggenerator; 3, the signal-receiving bell, and et the subscribers telephone. The circuits and connections are substantially as shown. Vhen the telephone is on the switch, the bell and generator are in the direct circuit of the line and the circuit of the line is grounded. When the telephone is off the switch, it is in the direct circuit of the line and the ground connection of the line at the subscribers station is removed.

The subscribers-station apparatus for metallic-circuit lines should preferably be connected into the line-circuit, so that the trans- `lator-coil at the central oice is in the normal circuit from the subscribers ground through his calling-generator to ground at the central office through the line-annunciator. The subscribers-station apparatus for the ground-circuit lines may be the usual form of apparatus for such lines.

The operation of the system is as follows:

When a subscriber wishes a connection7 he operates his generator and a current passes through the ground-circuit, which includes his generator and annunciator, and operates the annunciator. The operator on observing the call places one of her plugs D in the metallic socket of the line and places the switch Y so that her telephone is in circuit with the plug. A complete circuit is thereby established which can be traced from the ground through the battery B', the operators telephone, the switch Y to the plug, and thence to ground through the translator-coil of the line. The operator can then converse with the subscriber, the telephone-currents being translated from one circuit to the other through the translator, and can find out what line is wanted. She then tests for the line wanted, as will hereinafter be indicated, and if she Iinds that it is not already in use she places the other plug of the pair in the socket of the line. The translator-coils of the two lines are thereby included in a closed circuit, and the circuit is grounded through the telephone and battery. The operator then presses on the key-lever which is connected with the plug in the socket of the line wanted, and the calling-generator is thereby included in a closed circuit withthe translator-coil of the line, and induced currents will be sent to the line, which will ring the bell at the subscribers station. The operator then releases the -key and moves the switch Y, so that the retardation-coil .is connected in a third leg to the circuit of the two coils. The lines are then connected for conversation, and any telephone-current generated in the circuit of one line will be translated through the translators of the two lines to the circuit of the other line. The two subscribers can therefore carry on conversation. Vhen a plug is in the socket of any line, the local coil of the translator of the line is in closed circuit with the battery B', and the relay-armature being attracted the annunciator of the line is shunted orshort-circuited by the closing of the contact-points, so as to be practically out of the circuit in which it is placed.

lOO

IIO

When a subscriber desires to send a clearl IZO The test system is as follows: Vhcn an operator tests any line, she places her test-plug T on the metallic socket j of the line. If, then, the line is switched as described, a complete circuit is established from the ground through the test receiving instrument to the piece j tested, thence to the piecej, in which a switch-plug is inserted, and thence to ground through the battery B. The instrument will then sound or respond. lf, however, there is no plugin a socket of the line, the instrument will not sound. The operator can therefore determine on testing whether or not any line is in use. It is not necessary to the operation of the system that the central-office connections of the local translator-coils be made to ground as described. For instance, the translator-coils might be connected together by a metallic-circuit connection instead of going to ground, and in that case the connection of the test systems, the calling-generator, and the battery I3 would be preferable to this circuit connection instead of to ground, as described. It will be observed in this system that the circuits of any two pairs of coils which are temporarily connected together for conversation between the subscribers are in connection. This connection is, however, between the retardation-coils of the two pairs of plugs used in making the connections. W'ith properly-constructed apparatus and circuits the connections above described will not prevent the successful operation of the system. It will also be observed that when the local coils of two translators are left connected together for conversation between two subscribers there is a bridge-circuit across the circuit thereby established and between the two coils. This bridge-circuit, however, contains a retardation-coil, and therefore will not greatly decrease the amount of the telephone-currents which would otherwise pass through the complete circuit.

The operation relating to the line-annunciators whereby they are shunted or shortcircuited when the local coils of the line-translaters are switched for conversation may be obtained with other arrangements of circuits and apparatus than what I have described. For instance, there may be aseparate battery in the circuit of each pair of cords, which will operate the armature of a translator when connected in circuit with one of its coils.

The prevention of the operation of the line annunciator may be accomplished in other ways, one of which is shown in my application, Serial No. 403,714, where a branch circuit containing the line annunciator is opened when the line is switched; nor, broadly considered, is this part of my invention confined to the use of converters.

The operation relating to the retardationcoils whereby when two pairs of local coils connected together into complete circuits for conversation between subscribers and the circuits are connected together through retardation-coils may also be obtained with other arrangements of apparatus and circuits than what I have described.

My invention is not therefore limited to the particular arrangements of circuits and apparatus which I have described.

I claim as my inventionl. In a telephone-exchange system,a switchboard, telephone-lines, translators for said lines at the central oiiice, one coil of which is in the circuit of the line, switching apparatus to connect together any two of the other coils into a complete circuit for conversation between their two subscribers, and battery in circuit with any coil while thus connected, in combination with annunciators, one for each line, an armature for each translator, moved when its coil is thus connected with a battery, a pair of contacts for each armature, one connected to one side and the other connected to the other side of its lines annunciator, said contacts being normally open to each other but closed when the armature is thus moved.

2. In a telephone-exchange system,a switchboard, telephone-lines, translators for said lines at the central office, one coil of which is in the circuit of the line, switching apparatus to connect together any two of the other coils into a complete circuit for conversation between their two subscribers, and battery in circuit with any coil while thus connected, in combination with annunciators, one for each line, in the circuit of the line, an armature for each line, moved when its coil is connected with a battery, a pair of contacts for each armature, one connected to one side and the other connected to the other side of its lines annunciator, said contacts being normally open to cach other but closed when the armature is thus moved.

3. In a telephone-exchange system,a switchboard, telephone-lines, translators for said lines at the central oiiice, one coil of which is in the circuit of the line, switching apparatus to connect together any two of the other coils into a complete circuit for conversation between their two subscribers, and battery in circuit with any coil while thus connected, in combination with annunciators, one for each line, an armature for each line, automatically moved when its coil is thus connected with a battery, a pair of contacts for each armature, one connected to one side and the other connected to the other side of its lines annunciator, said contacts being normally open to each other but closed when the armature is thus moved.

4. In a telephone-exchange system,a switchboard, telephone-lines, translators for said lines at the central office, one coil of which is in the circuit of the line, switching apparatus to connect together any two of the other coils into a complete circuit for conversation between their two subscribers, and battery in circuit with any coil while thus connected, in combination with annunciators, one for each line, in a ground connection of the line, an armature for each line, automatically moved when its coil is thus connected with a battery, a pair of contacts for each armature, one connected to one side and the other connected to the other side of its lines annunciator, said contacts being normally open to each other but closed when the armature is thus moved.

5. In a tclephoneexchange system, sub- ICO ' switches on a switchboard, one for each subscribers telephone-lines, annunciators, one

foreach line, each having its magnet permanently 1n circuit connection with its line,

1 ing a contact-piece adapted to form connection with said contact-piece of the switch of a subscribers talking-circuit when the plug is placed in said switch to switch said talking-circuit for conversation, said contactpieces of the pair of plugs being connected together by a flexible switch-conductor, and a battery connected on one side to said switchconductors of said pairs of plugs and on its other side to circuit connections, one through.

the electromagnetic device of each line to said contact-piece of the switch for the; line.

6. In a telephone-exchange system,niulti ple switchboards, subscribers telephonelines, annunciators 011efor each line, each having its magnet permanently in circuit con'- nection with its line, switches, one on each board for the talking-circuit of each subscriber and having each a contact-piece, electromagnetic devices one for each line, each having a different electromagnet than said annunciator-magnet of the line actuated when a current is established through it and con'- trolling the line-annunciator that it will not be then operated by a current sent over the line, pairs of switch-plugs at each board, each plug having a contact-piece adapted to form connection at its board with said contactpieces of the switches of the subscribers talking-circuits when the plug is placed in either of said switches to switch a talking-circuit for conversation, said contact-pieces of each pair of plugs being connected together by a flexible switch-conductor, a battery or batteries connected on one side to said switch-conductorsof said pair of plugs and connected on the other side in circuit connections, one through the electromagnetic device of each line to said switch contact-pieces of the switches of the line, and test receiving instruments, one at each board, each connected on one side to said last-named side of said battery or batteries and on its other side to a test plug or device adapted to be brought for testing into connection with either of said switch contact-pieces at its board.

7. In a telephone-exchange system, multiple switchboards, subscribers telephonelines, switches, one on each board for the talkin g-circuit of each subscriber and having each a contact-piece, electromagnetic devices one for each line, pairs of switch-plugs at each board, each plug having a contact-piece adapted to form connection at its board with said contact-pieces of the switches of the subscribers talking-circuits when the plug is placed in either of said switches to 'switch a talkin g-circuit for conversation, said contact-pieces of each pair of plugs being connected together by a flexible switch-conductor, a battery conadapted to be brought for testing into connection with either of said switch contact-pieces at its board.

8. In a telephone-exchange system, multiple switchboards,subscribers metallic-circuit telephone-lines, switches, one on each board for the talking-circuit of each subscriber and having each a contact-piece not connected to the line, resistances, one for each line, pairs of switch-plugs at each board, each plug having a contact-piece adapted to form connection at its board with said contact-pieces of the switches of the subscribers talking-circuits when the plug is placed in either of said switches to switch a talking-circuit for con-l versation, said contact-pieces of each pair of plugs being connected together by a flexible switch-conductor, a battery connected on one side to said switch-conductors of said pairs of plugs and connected on the other side in circuit connections, one through the resistance of each line to said switch contact-pieces of the switches of the line, and test receiving instruments, one at each board, each connected on one side to said last-named side of said battery or batteries and on its other side to a test plug or device adapted to be brought for testing into connection with either of said switch contact-pieces at its board.

9. In a telephone-exchange system, the combination of a switch board or boards, subscribers telephone-lines or talking-circuits, switches therefor on the board or boards, an individual annunciator permanently, that is whether the line is switched or not, included in closed circuit with each line and operated by calling-current sent through it, a clearingout annunciator, means for connecting any two lines together for conversation and connecting the clearing-out annunciator with or into their circuit, a local circuit including a battery that is completed when any two lines are thus connected, a subscribers callinggenerator located in closed circuit with either subscribers line thus connected and sending clearing-out currents operating said clearingout annunciator, and electromagnetic means included in the local circuit and operated by the current from the battery therein, shunting the line-annunciator and thereby preventing the operation of the line-annuncia- IOO IIO

i combination ot' a switch board or boards, subscribers telephone-lines or talking-circuits, switches therefor on the board or boards, an individual annunciator permanently, that is whether the line is switched or not, included in closed circuit with each line and operated by calling-current sent through it, aclearingout annunciator, means for connecting any two lines together for conversation and connecting the clearingout annunciator with or into their circuit, a local circuit including a battery that is completed when any two lines are thus connected, a subscribers callinggenerator located in closed circuit with either subscribers line thus connected and sending clearing-out currents operating said clearingout annunciator, and electromagnetic means included in the local circuit and operated by the current from the battery therein, to prevent the operation of the line-annunciators when clearing-out currents are sent over the line.

1l. In a telephone-exchange system, the combination of a subscribers telephone-line,

a call-annunciator included in said line, a

normally open short circuit around said annunciator, and means for closing such short circuit by the act of switching the line for conversation.

12. In a telephone-exchange system, the combination of a switchboard, two telephonelines, each having a socket or switching con nection on said board, a subscribers generator at each subscribers station, a call-annun! ciator included in or permanently connected with each line at said board, switch-plugs and their cord connections for placing said lines in communication for conversation, a clearingout annunciator in the equipment of said cord connections, and adapted to be operated by a clearing-out current sent from either subscribers generator, a normally open short circuit around the call-annunciator of each line, and means for closing such short circuits by the act of placing the lines in eommunt, cation for conversation, substantially as dcscribed.

In testimony whereof I have hereunto subscribed my name.

MIL() G. KELLOGG. Witnesses:

CALVIN DE WOLF, FRANCES D. KELLOGG. 

